Hearing aid



FIG. 1 is a front view of a hearing aid, showing our new design including portions in dashed lines shown herein and throughout the figures to illustrate an environmental structure of the hearing aid, the dashed line portions shown throughout the figures forming no part of the claimed design;

FIG. 2 is a side view thereof taken from the right of FIG. 1;

FIG. 3 is a side view thereof taken from the left of FIG. 1;

FIG. 4 is a bottom view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a rear view thereof; and,

FIG. 7 is a perspective view thereof. 

The ornamental design for a hearing aid, as shown and described. 